There are currently different techniques for characterizing mechanical, tribological, physiochemical or other properties of metals, non-metals, chemicals, materials, surfaces, and lubricants, which use controlled mechanical action on the surface of object to characterize a property of the surface. In these techniques, a handheld tool or tool held by some mechanical means exerts a force on the surface to be characterized which is usually normal to the surface. Also, in some cases when motion is imparted to the hand-held tool or tool held by some mechanical means on the surface to be characterized a friction force is always produced in the direction opposite to the direction of motion. The measurement of the frictional force and the applied load with high precision and reproducibility are conditions necessary for many characterization techniques. Further, to characterize different objects and materials such as ceramics, metals, metal alloys, polymers, composite materials, non-metals, physical objects, regions of animal and human body, hard surface coatings, solid and liquid lubricants, etc., which have very different mechanical properties the device needs to have a broad range of measuring capacity.
Characterization of surface properties of regions of human body or animal body, plays an important role as many consumer products are applied to the skin, hair, teeth and other regions of body. Consumer preferences are influenced by various factors, including product effectiveness, the feel of the product, fragrance, durability, ease of rinsing, etc. One way to determine consumer preferences is by conducting consumer marketing tests, in which a representative group of consumers provide feedback after using a product. Consumer marketing tests have several drawbacks, because consumers must be appropriately selected and compensated for their time, hence such tests are expensive and time consuming. Also, human feedback is inherently subjective, and may raise concerns about reliability, and the analyses, that can be performed after application, are limited.
There are several methods and devices for characterizing surface properties of regions such as skin, teeth, hair etc., One of which is use of a flexible member with a well determined stiffness constant. This flexible member is usually located between an attachment and the hand-held tool which exerts force on the sample. The normal force exerted by the hand-held tool on a surface is determined by the deflection of the flexible member in the direction normal to the surface of the sample. The frictional force resulting from the friction between the hand-held tool and the surface to be characterized is determined by the deflection of the flexible member in the direction opposed to the direction of motion.
In conventional devices the deflection of the flexible member is measured by means of a sensor, which by way of illustration can be one of the following types: fiber optic, capacitive, inductive, laser interferometric sensor, strain gauge or the like. One of the most widely used ones is the strain gauge. Another known conventional device for evaluation of frictional and normal loads between a two surfaces or objects comprises a measuring arm having a measuring sensor capable of measuring a frictional force being exerted on a tip. The devices described above measures either one of the frictional force or the stiffness constant, but does not provide a means to determine the motion of the hand held device and to estimate the co-efficient of friction between the surfaces to be characterized. Further, these devices are used only for a very narrow and well defined range of parameters, orientation and motion. Also, these device are generally used only under defined or controlled conditions. Thus, the modes of operation and evaluation of these devices are limited. Furthermore, the conventional devices requires a skilled operator to handle the device under controlled laboratory conditions.
Thus there exists a need for an apparatus to estimate the co-efficient of friction between two surfaces or members, without the need for a skilled operator. Further, there exists a need for an apparatus that can perform evaluations for a wide range of parameters, orientation and motion. Furthermore, there also exists another need to estimate the operating conditions during the evaluations. In addition, there exists yet another need to carry out these evaluations without controlled conditions. Additionally, there exists a need for an apparatus that can overcome the aforementioned drawbacks. The principle object of the embodiments herein is to provide an apparatus to estimate co-efficient of friction between a first sample member and a second sample member.